The present invention relates to apparatus for exchanging a film roll in a machine for wrapping a product with wrapping film while the product is either stationary or rotated around a horizontal axis. The wrapping machine includes a rotating wrapping crank which carries a film distribution sledge having tension rolls and which carries a roll of wrapping film. The film is wrapped around the product as the wrapping crank rotates.
The invention also relates to a method for exchanging a film roll during operation of the wrapping machine wherein an old film roll is removed from the film distribution sledge and a new film roll shifted in its place.
Two different arrangements are commonly used in wrapping film or the like around various products being packaged. In the first arrangement, the product to be packaged is situated on a revolving base. Film is wrapped around the product as the product itself is rotated on the revolving base. This arrangement has a number of drawbacks. For example, when the product being wrapped comprises a plurality of units, it is difficult to maintain the units in a compact assembly on the revolving base. It is also difficult and expensive to provide additional functions and to automate the packaging operation.
According to the second arrangement in common use, the product being packaged is maintained in a stationary position in the wrapping machine while the film is wound around the product, i.e., the film roll is moved around the product. This arrangement is considered to be more advanced than the arrangement where the product is rotated, and, among other things, can be more easily provided with additional functions to facilitate automation of the wrapping operation.
However, in neither of the arrangements discussed above has it been possible to automate the exchanging of the wrapping film rolls such as when the film roll is exhausted.
In particular, at the present time, the rolls have been manually exchanged. The wrapping film roll must always be changed when the film has broken for some reason, or of course, when the film has been exhausted from the roll. Due to the necessity of manually exchanging the wrapping film rolls, it has been necessary to limit the weight of the wrapping film rolls to a maximum of about 30 kg so that the new film roll can be lifted into position. However, this in turn results in the wrapping film being exhausted in a relatively short time making it necessary to exchange the rolls on a more frequent basis than is desired. Further, the manual exchange of wrapping film rolls involves certain safety risks and hazards.
Another drawback inherent in the manual exchange of film rolls in a wrapping machine is that the leading end of the film on the new film roll had to be threaded between a number of tension rolls mounted on the film distribution sledge. This is a cumbersome operation involving the risk of the operator's fingers becoming caught between the rolls.